In a photolithography process for manufacturing semiconductor devices, a resist pattern is formed on the surface of a semiconductor wafer, as follows. Specifically, a photo-resist is applied onto the surface of a semiconductor wafer to form a resist film. Then, a predetermined pattern is formed on the resist film by light exposure. The light-exposed portion or non light-exposed portion of the resist film is selectively dissolved by a developing solution. The developing solution is washed out by a rinsing liquid, such as purified water. Then, the semiconductor wafer is rotated at a high velocity to remove the rinsing liquid and dry the wafer.
In recent years, in order to increase the integration degree of semiconductor devices, the line width of resist patterns is increasingly miniaturized and the density of circuit patterns is becoming higher. Where the line width of resist patterns is smaller, a problem arises such that the patterns are deformed or bent (so called pattern fall) due to lack of the resist hardness.
The pattern fall of a resist pattern is caused by a force of the surface tension of a rinsing liquid. It is known that this force is generated when the liquid level of a rinsing liquid becomes lower than the top surface of a resist pattern, while the rinsing liquid is removed from a substrate and the resist pattern is dried. Accordingly, as long as the entirety of a resist pattern is immersed within a developing solution or rinsing liquid, no pattern fall is caused. In light of this, Jpn. Pat. Appln. KOKAI Publication No. 7-20637discloses a method for preventing pattern fall, as follows. Specifically, after a resist film is subjected to a developing process and a rinsing process, a rinsing liquid is solidified when the rinsing liquid is still left on the resist film. Then, the solidified rinsing liquid is sublimated.
However, this method cannot sufficiently prevent recent resist patterns having a smaller line width from causing pattern fall. Further, since solidification and sublimation of a rinsing liquid are required, the structure of a processing apparatus becomes complex.